Marc Williams, after less than two years as principal of the Secondary School for Journalism in Park Slope, quit amid an investigation of course-credit schemes exposed by The Post in July.

A teacher said Williams turned a blind eye when a student got a passing grade in a course by taking online tests — with help from a classmate.

Williams has been made a “case manager” in the Department of Education’s human resources department, officials said. His new $127,443 salary is less than the $156,131 he made last school year, but “it was not a demotion,” said DOE spokesman Michael Aciman.

As DOE investigators grilled teachers about the credit schemes, the 236-student school was thrown into more turmoil this month.

Annette RenaudHelayne Seidman

Interim Acting principal Livingston Hilaire learned — three days before the start of classes — that he had to give up two classrooms for Millennium Brooklyn HS, a high-performing school that shares the John Jay building, causing a massive scheduling headache.

“The DOE intentionally sabotaged our school,” charged Annette Renaud, the former parent association president and a whistleblower on the grade schemes. “This is class warfare.”

Hilaire angrily walked out, announcing that Angelo Marra, another unassigned principal, would take the helm, but a DOE officials said Hilaire was still in charge and that Marra would assist.